War of the Burning Sky is dungeon-lite, and is designed to handle different campaign lengths and start- or end-points. It focuses on a magical war that sees the heroes in the role of special operatives, trying to rally an alliance against the overwhelming magical might of the Ragesian Empire. You can start at 1st level and go all the way through 20th or higher, but the adventures are arced so that you could start (or end) at the 4th or 8th adventure instead.
Want a low-level intelligence mission? Go from 1st to 8th level in the first four adventures, stealing military plans, getting them to the resistance, and then playing a prominent role in a major battle.
Want some more mid-level questing? Go from 7th to 16th level in adventures four through eight, where the heroes start by helping a nation hold back the first assault by Ragesia, and then they set out to recover the assassinated Emperor, raise him, and strike back against the usurper.
Want high-level world-shattering events? Go from 15th to 20th level in the eighth through twelfth adventures, starting with a mission to destroy a super-weapon, only to realize that the evil empress is being aided by nightmare beasts from the underdark in an effort to scorch the earth.
What level is he thinking of running? More details of the campaign saga can be found at the link in my sig.
(And if he does decide to do something else, Red Hand of Doom was pretty fun when I played it.)